Communication system and method of routing calls to an end point

ABSTRACT

A method of routing a call includes sending a second query when a telephone number mapping (ENUM) database does not identify an internet protocol (IP) address associated with a called number in response to a first query. The second query is directed to a local number portability (LNP) database to determine whether the called number includes a ported number having an associated local routing number (LRN).

CLAIM OF PRIORITY

The present application claims priority from and is a continuation of U.S. patent application Ser. No. 11/120,142 filed on May 2, 2005 and entitled “Communication System and Method of Routing Calls to a Terminating End Point,” the contents of which are expressly incorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to a system and method of routing calls.

BACKGROUND

With certain conventional communication systems, the detection of Internet protocol (IP) terminating end points and ported public switch telephone network (PSTN) endpoints involves two separate process steps and two separate transactions within a telephony system. The detection of IP addresses involves a telephone number mapping (ENUM) query and ported number detection involves a local number portability (LNP) query. The two separate transactions and separate queries increases the cost and adds to latency of the call setup process. The increased cost and call latency may also impact call processing performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general diagram that illustrates a communication system with an ENUM service provider;

FIG. 2 is a flow chart that illustrates a method of routing a call using the communication system of FIG. 1; and

FIG. 3 is a flow chart that illustrates a method of processing a combined ENUM/LNP query at the ENUM service provider.

DETAILED DESCRIPTION

In a particular embodiment, a method of routing a call includes sending a second query when a telephone number mapping (ENUM) database does not identify an internet protocol (IP) address associated with a called number in response to a first query. The second query is directed to a local number portability (LNP) database to determine whether the called number includes a ported number having an associated local routing number (LRN).

In another embodiment, an apparatus includes a service provider node to send a first query to a service provider resource that includes a telephone number mapping (ENUM) database coupled to a local number portability (LNP) database. The first query is associated with a called number. When an internet protocol (IP) address associated with the called number is not provided by the service provider resource in response to the first query, the service provider node is to receive the response from the service provider resource after a second query that is sent from the ENUM database to the LNP database.

In another embodiment, a service provider apparatus is disclosed and includes a telephone number mapping (ENUM) database. The ENUM database is configured to provide an internet protocol (IP) address associated with a called number when the IP address is stored at the ENUM database in response to a first query. When the IP address is not stored at the ENUM database, the ENUM database is configured to request a local routing number (LRN) associated with the called number via a second query that is sent from the ENUM database to a local number portability (LNP) database.

Referring to FIG. 1, a communication system 100 is illustrated. The communication system 100 may be used to provide a single query to determine if a number is an internet protocol (IP) endpoint or a ported number in a public switch telephone network (PSTN). The communication system 100 includes the PSTN 104 and a service provider network node 102. The communication system 100 also includes an Internet protocol (IP) backbone network 112 that is coupled to a remote SS7 and ENUM service provider 106. The service provider network node 102 includes a media gateway 120 and a soft switch 122. The service provider network node 102 is coupled to the PSTN 104 via a time division multiplex (TDM) link 114. In a particular embodiment, the TDM link 114 is a T1 line.

The service provider node 102 is coupled to the SS7 and ENUM service provider 106 via an IP connection 110 and also via a direct connection 108. The SS7 and ENUM provider 106 includes SS7 equipment 130 including a local number portability (LNP) database 132. The SS7 and ENUM service provider 106 also includes a telephone number mapping (ENUM) database 134 which is coupled to the LNP database 132 over a data link, such as an SS7 link or an IP data link.

During operation, the service provider network 102 receives a call from the PSTN 104 over the TDM link 114 at the media gateway 120. The call request is then forwarded to the soft switch element 122 for routing. The soft switch 122 receives the call request that includes a called number to identify a called party. In response to receiving the call request, the soft switch 122 executes program logic that sends a combined telephone number mapping (ENUM) and local number portability (LNP) query to the remote ENUM database 134 over the IP backbone network 112. The combined query is illustrated in FIG. 1 as a data message 140.

The data message 140 related to the combined ENUM/LNP query includes the called number. The called number may, in a particular embodiment, be a ten digit E.164 type number. The E.164 number may have been originally dialed by a caller at a telephone device such as a voice over IP (VoIP) end user device.

The ENUM database 134 receives the ENUM query via the data message 140. The received data message query is a combined ENUM and LNP query that is sent from the service provider node 102. The ENUM database, in response to receiving the combined ENUM/LNP query, accesses the ENUM internal database using the called number (such as the E.164 number) to determine whether the database includes an Internet protocol (IP) address that is associated with the called number. When the access to the ENUM database identifies an IP address, then the IP address may be provided in a response message from the ENUM database to the service provider network node 102. An example response message to the combined ENUM/LNP query is illustrated as the data message 142 passed over the IP backbone network 112.

When the access to the ENUM database 134 does not identify an IP address, then the particular called number is indicated as not having an Internet protocol network termination. In this case, the ENUM database 134 sends a local number portability query to the local number portability (LNP) database 132 over the link coupled therebetween. The LNP database 132 receives the LNP query from the ENUM database 134. The LNP query includes the called number and the LNP database 132 is accessed to determine whether the called number is identified as a ported number that has an associated local routing number (LRN). In the event that the called number has an associated local routing number, then the LNP database 132 provides the local routing number (LRN) associated with the ported number to the ENUM node 134. The LRN is used to route a call to a uniquely identified switching node of a circuit switched network, such as the PSTN 104.

In the event that the LNP database query indicates that the called number does not have an associated ported number, then the LNP database does not retrieve an LRN for the called number and instead, the LNP responds to the query from the ENUM database 134 with an indication that the called number is not a ported number. In a particular embodiment, the called number itself is returned as the response to the LNP database query to indicate that the called number does not have a ported number. After the ENUM database 134 receives the response to the LNP query from the LNP database 132, the ENUM database 134 prepares a response to the original combined ENUM/LNP query that was received from the service provider node 102. The response to the combined ENUM/LNP query includes one of an IP address to identify a node of an IP network, a local routing number (LRN) that is associated with detection of a ported number by the LNP database 132, or the called number itself, to indicate that there is no IP address in the ENUM database 134 and there is no ported number found within the LNP database 132. Thus, the response to the combined ENUM/LNP query may include an IP address for a direct VoIP connection, an LRN to identify a unique switching node of a circuit switched network, or the called number itself to identify a standard routing to the called number without requiring local number portability and without providing access to an IP address of an IP network. Thus, the response to the combined ENUM/LNP query provides information regarding portability and whether a packet switched or circuit switched routing should be utilized for the particular call to the called number.

Since each extra step in a call setup process increases the latency delay time and the associated costs of using an LNP database and an ENUM database, the disclosed system and method beneficially provides a single step using a combined ENUM/LNP query in response to detecting an IP or ported PSTN end point, thereby saving call setup time and the associated charges associated with the LNP/ENUM databases.

Referring to FIG. 2, an illustrative method of using the communication system 100 is shown. A method of determining a telephony network node for routing a call is shown. The method includes receiving a call request at a service provider node where the call request includes a called number to reach a called party, as shown at 202. The method further includes sending a combined telephone number mapping (ENUM) and local number portability (LNP) query from a service provider node to a remote ENUM database, as shown at 204. It should be noted that the combined ENUM/LNP query may include the called number, such as an E.164 number. The method further includes receiving a response to the combined ENUM/LNP query at the service provider node where the response includes either an Internet protocol address that identifies the node of an IP network, a local routing number (LRN) associated with a ported number and used to route the call to a uniquely identified switching node of a circuit switch network, or an indication that the called number is not a ported number such that the called number can be used to route the call to the called party. The response method step is illustrated at 206.

In a particular embodiment, the ENUM database makes a query after receiving the combined ENUM/LNP query message to an LNP database prior to providing the response to the combined ENUM/LNP query. In addition, in a particular embodiment, the query from the ENUM database to the LNP database includes the called number and the LNP database maps the called number to the local routing number (LRN) when the called number is identified as a ported number. The query from the ENUM database to the LNP database may be sent over an SS7 link or an IP data network connection. Alternatively, a proprietary data communication mechanism may be utilized such that the ENUM database may query the contents of the LNP database and receive the local number portability information.

Referring to FIG. 3, a method of routing a call that may be used in connection with the communication system 100 is shown. The method includes receiving a combined telephone number mapping (ENUM) and local number portability (LNP) query from a service provider node at an ENUM database. The combined ENUM/LNP query includes a called number, as shown at 302. The method further includes accessing the ENUM database using the called number to identify an IP address that may be associated with the called number, as shown in 304. When access to the ENUM database does not identify an IP address, indicating that the called number is not an IP termination call, the ENUM database sends a query to a local number portability (LNP) database, as shown at 306. The ENUM database receives a response from the LNP database, as shown at 308. The response from the LNP database includes either a local routing number or an indication that the called number is not a ported number, such as a return of the same called number. The method further includes sending a response to the combined ENUM/LNP query to the service provider node after accessing the ENUM database and the LNP database (for non IP calls), as shown at 310. In a particular embodiment, the response to the combined ENUM/LNP query includes an IP address that identifies a node of an IP network, an LRN associated with a ported number, or an indication that the called number is not a ported number such that the called number can be used to route the call.

The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. 

1. A method of routing a call, the method comprising: when a telephone number mapping (ENUM) database does not identify an internet protocol (IP) address associated with a called number in response to a first query, sending a second query, the second query directed to a local number portability (LNP) database to determine whether the called number comprises a ported number having a local routing number (LRN).
 2. The method of claim 1, further comprising receiving the LRN in response to the second query and issuing a response to the first query, the response comprising the LRN.
 3. The method of claim 2, wherein the response is issued to a node of a service provider network.
 4. The method of claim 2, wherein the LRN enables routing of the call to uniquely identified switching node of a circuit switched network.
 5. The method of claim 1, further comprising issuing a response to the first query, the response comprising an indication that there is no LRN associated with the called number in the LNP database.
 6. The method of claim 5, wherein the indication comprises the called number.
 7. The method of claim 1, further comprising issuing a response to the first query, wherein the response comprises the IP address.
 8. An apparatus comprising: a service provider node to send a first query to a service provider resource, the first query associated with a called number, wherein the service provider resource comprises a telephone number mapping (ENUM) database coupled to a local number portability (LNP) database; and when an internet protocol (IP) address associated with the called number is not provided by the service provider resource in response to the first query, the service provider node is to receive the response from the service provider resource after a second query, wherein the second query is sent from the ENUM database to the LNP database.
 9. The apparatus of claim 8, wherein when the IP address associated with the called number is not provided by the service provider resource in response to the first query, the response comprises one of a local routing number (LRN) associated with the called number and an indication that the LRN is not available from the LNP database.
 10. The apparatus of claim 9, wherein the indication comprises a return of the called number.
 11. The apparatus of claim 10, wherein when the response includes the return of the called number, the called number is used to route the call to a called party.
 12. The apparatus of claim 8, wherein the called number is a ten digit number.
 13. The apparatus of claim 8, wherein when the response identifies the IP address, the service provider node is to route the call using a voice over internet protocol (VoIP) connection to a terminating IP network node identified by the IP address.
 14. A service provider apparatus comprising: a telephone number mapping (ENUM) database, the ENUM database configured to: provide an internet protocol (IP) address associated with a called number when the IP address is stored at the ENUM database in response to a first query; and when the IP address is not stored at the ENUM database, request a local routing number (LRN) associated with the called number via a second query sent from the ENUM database to a local number portability (LNP) database.
 15. The service provider apparatus of claim 14, wherein the first query is received from a service provider node.
 16. The service provider apparatus of claim 14, wherein the first query includes the called number.
 17. The service provider apparatus of claim 14, wherein the ENUM database includes logic to initiate the second query to the LNP database.
 18. The service provider apparatus of claim 14, wherein the service provider apparatus is further to provide, in response to the first query, the LRN associated with the called number or an indication of an absence of the LRN at the LNP database.
 19. The service provider apparatus of claim 18, wherein when the LRN is provided, the called number comprises a ported number in a public switch telephone network (PSTN).
 20. The service provider apparatus of claim 18, wherein when the LRN is not provided, the indication comprises the called number. 